1. Field of the Invention
The present invention relates to a copolymer of a polyacrylic acid derivative or a polymethacrylic acid derivative each having cinnamylideneacetic acid ester as a pendant group. More particularly, the invention relates to a functional group-containing polymer containing 1 to 90 mol percent of repeating units having a cinnamylideneacetic acid ester pendant group and also to a composition containing the functional group-containing polymer. The invention relates further to a method of preparing the functional group-containing polymer.
2. Description of the Prior Art
Various investigations have hitherto been made on systems which undergo changes in solubility, adhesiveness, or hardness at portions irradiated with light, thermal radiations, particle rays, electromagnetic waves, etc., and some of such systems are now being practically used.
With regard to functional group containing or reactive compounds employed in such conventional techniques, studies are known on .alpha.,.beta.-unsaturated carboxylic acid derivatives and .alpha.,.beta.-unsaturated carbonyl compounds as described in, e.g., J. Kosar; Light Sensitive Systems; Chapter IV, John Wiley & Sons, New York, 1965, and A. Schonberg; Preparative Organic Photochemistry; Chapter 8, Springer-Verlag, New York, 1968, studies on the photocyclobutane ring-forming addition reaction of cinnamic acid derivatives of these unsaturated carboxylic acids as described in, e.g., P. Silber; Ber. Dtsch. Chem. Ges., 35, 4128 (1902), and studies on polymers containing cinnamic acid ester groups for applications to photosensitive systems as described in, e.g., A. Schonberg; Preparative Organic Photochemistry, Springer-Verlag, Chapter 8 as described above and also as described in the specifications of U.S. Pat. Nos. 2,835,656; 3,357,831; 3,737,319; 3,418,295; 3,647,470; 3,409,593; 2,956,878; 3,173,787; 3,023,100; and 3,066,117.
The aforesaid polymers containing cinnamic acid esters as the functional groups are those prepared by the reaction of hydroxy group-containing polymers (e.g., polyvinyl alcohol) and cinnamic acid esters. However, since polyvinyl alcohol is only sparingly soluble in ordinary solvents, there are disadvantages in that a large amount of solvent such as pyridine is required, a very long period of time is required for completing the reaction, and colored polymers are obtained. To minimize or eliminate these aforesaid disadvantages encountered in the production of these polymers, preparation of the polymer esters in the presence of an inorganic base at low temperature utilizing a Schotten-Baumann method has been the approach used, but since the reaction system is heterogeneous, it is difficult to control the temperature of the reaction system using this method.
In addition to the above-described disadvantages in the production of the polymers, there is also the disadvantage that the specific sensitivity of cinnamic acid esters is much lower than that of cinnamylideneacetic acid. Therefore, attempts to obtain polymers having cinnamylideneacetic acid esters as pendant groups have been made.
For instance, a method (1) wherein a functional group-containing polymer is obtained by reacting polyvinyl alcohol and cinnamylideneacetic acid chloride and a method (2) wherein a functional group-containing polymer is obtained by polymerizing a vinyl ether or a styrene derivative each having a cinnamylideneacetic acid ester group using an ionic polymerization initiator as a catalyst are known.
However, since method (1) is a reaction in a heterogeneous system at low temperature, the operations required for controlling the rate of reaction and reaction temperature are complicated.
For example, in U.S. Pat. No. 3,257,664, detailed experimental conditions concerning the reaction of a polymer (polyvinyl alcohol) with cinnamylidenacetyl chloride are described as follows:
a. in Example 4, a mixture of 22 g of polymer and 200 ml of pyridine was heated on a steam bath for 1 hour with stirring and an additional 200 ml of pyridine is added before the dropwise addition of melted cinnamylideneacetylchloride. The reaction is further conducted at 50.degree.C for 4 hours. The yield is about 91 percent.
b. in Example 7, 380 ml of pyridine is used to swell (not to dissolve) 22 g of a polymer (polyvinyl alcohol) on a steam bath overnight. After the reaction of the polymer with an acid halide, the reaction mixture is heated at 50.degree.C for 4 hours and diluted with 700 ml of acetone before precipitation into cold water. The resulting polymer is further purified by washing with water 4 times.
In these Examples, the polymer concentration is only 5.5 to 5.8 weight percent to the base (pyridine). Yet, as shown in the disclosure quite clearly, the polymer is only swollen by pyridine. That is, a heterogeneous, complicated reaction is contemplated from these reaction conditions.
To overcome these difficulties shown in U.S. Pat. No. 3,257,664, a modified process has been developed to obtain a cinnamylideneacetoxy functional group-containing polymer as described in U.S. Pat. No. 3,761,280 as follows.
In the Example, an isocyanate group containing cinnamylideneacetate is reacted with a polymer (polyvinyl alcohol). The isocyanate is used because it is more reactive with hydroxyl groups than an acid halide. Unfortunately, although the isocyanate must be synthesized using very complicated procedures such as using poisonous conditions as through phosgenation, a highly light sensitive functional polymer is obtained. However, the polymer concentration is only 5 weight% (that is 10 g of polymer is swollen in 200 ml of pyridine) and the reaction is conducted at 50.degree.C for 3 hours.
The reaction conditions shown above are very severe, heterogeneous and complicated compared with those of the present invention (i.e., wherein homogeneous, mild reaction conditions are employed) as will be described hereinafter.
In addition, since method (2) utilizes an ionic polymerization reaction, the method is accompanied with the disadvantages that the polymerization reaction is greatly hindered due to the influence of humidity or moisture with the reaction sometimes ceasing completely, the operation conditions for conducting the reaction are complicated as a result of the low-temperature system, and further only gelled products are obtained using radical polymerization.
An object of this invention is to provide a novel functional group-containing polymer which can be easily prepared using a homogeneous reaction system without being accompanied by the aforesaid disadvantages.
Another object of this invention is to provide a method of preparing the functional group-containing polymer.
Still another object of this invention is to provide a reactive composition containing the functional group-containing polymer.
The inventors have already investigated acrylates or methacrylates each having a cinammic acid ester group and also the polymerization of such as described in U.S. Pat. No. 3,770,443. The present invention is an extension and improvement of our previous invention.